1A photographic process using iron compounds as developing agents; = energiatype .
rare after mid 19th century.
2A photograph taken using a process by which negatives are taken directly on black-enamelled or painted thin iron plates covered with photographic emulsion, the dark background giving the appearance of a positive image.
3In full "ferrotype plate". A thin iron plate used in this process.
Ferrotype plates were also adapted for use as a diaphragm in the mouthpiece and earpiece of a telephone.
Mid 19th century. From ferro- + -type.